Mathematic modeling of the salt deposits growing on the tubing during debrining for gas storage salt cavern

Abstract

Salt deposits growth during debrining of salt cavern construction may block the debrining inner tubing (DIT) and influence the efficiency of debrining. A novel coupled model for the salt deposits growing on the DIT during debrining is built according to the salt deposits growth mechanisms and heat transfer principle. A finite element model is proposed, which considers the coupling of salt deposits growth and of brine heat transfer. A device used to simulate the salt deposits growing on the tubing during debrining was developed and a simulating experiment was carried out. The model is validated by experimental results. The relative error of salt deposits total masses on the debrining tubing between the model result and the experimental result is 3 %. A-1 cavern of Jintan UGS is taken as an example. The rules of salt deposits growing and brine temperature changing were researched. Results show that the salt deposits thicknesses increase with the decrease of depth. It is similar to the experimental results. The salt deposits thicknesses maximum is 6.86 mm after continuous debrining for 24 h, much less than the radius of the DIT. It is suggested to increase the continuous debrining time to 24 h for increase the efficiency of the debrining. This study can provide a theoretical foundation and a technological reference for predicting the salt deposits growth during debrining.